Research Report Progranulin deficiency leads to enhanced cell vulnerability and TDP-43 translocation in primary neuronal cultures Aobo Guo a , Lucia Tapia b , Shernaz X. Bamji a, b , Max S. Cynader a , William Jia a, ⁎ a Brain Research Center, 2211 Wesbrook Mall, University of British Columbia, Vancouver, BC, Canada b Department of Cellular & Physiological Sciences, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada ARTICLE INFO ABSTRACT Article history: Accepted 26 September 2010 Available online 1 October 2010 Null mutations in the progranulin gene (PGRN) have been identified as a major cause of frontotemporal dementia with ubiquitinated inclusions. In this disorder, ubiquitinated, aggregated protein inclusions of a normally nuclear-located RNA processing protein called TAR DNA binding protein (TDP-43) accumulate in the neuronal cytoplasm (FTLD-TDP). To determine whether aspects of this clinical pathology can be established in primary cultures of mouse cortical neurons, PGRN levels were knocked down in neuronal cultures using lentiviral vectors to introduce mouse PGRN–siRNA constructs and subsequently rescued by overexpressing PGRN using a human PGRN-expressing lentiviral vector. The depletion of PGRN enhanced caspase-3 activation, and the PGRN-deficient neurons demonstrated enhanced vulnerability to normally sublethal doses of N-methyl-D-aspartic acid (NMDA) and hydrogen peroxide (H 2 O 2 ). TDP-43 protein levels were markedly increased in the cytoplasm of PGRN-deficient neurons relative to nuclear levels, which is similar to observations in the brains of FTLD-TDP patients. Our results establish a neuronal culture model of the PGRN deficiency, which displays some of the important phenotypic characteristics of the early stages of the disease. The results further suggest that the seeds of this form of frontotemporal dementia may be sown early in life. © 2010 Published by Elsevier B.V. Keywords: FTLD-U Progranulin Cortical neuron RNA interference Apoptosis TDP-43 1. Introduction Mutations in the progranulin gene (PGRN), located on chromo- some 17q21, have been identified as a major cause of familial frontotemporal dementia (Baker et al., 2006; Cruts et al., 2006). All known PGRN mutations result in the reduction of progranu- lin protein expression, rather than the accumulation of mutant protein (Baker et al., 2006). Ubiquitin-positive, and tau- and α- synuclein-negative inclusions are hallmarks of both frontotem- poral lobar degeneration with ubiquitin-positive inclusions and amyotrophic lateral sclerosis. TDP-43 (TAR DNA binding protein of 43 kDa) is a major component of the pathological inclusions observed in patients with both disorders (Dickson et al., 2007; Mackenzie et al., 2007; Tan et al., 2007). The pathologic form of TDP-43 has been shown to be hyperphosphorylated, ubiquiti- nated, and cleaved to generate C-terminal fragments that form the inclusions (Neumann et al., 2006). Moreover, this pathologic form of TDP-43 is observed predominantly in the affected regions of the central nervous system (Neumann et al., 2006). The observation that hyperphosphorylated and ubiquitinated TDP-43 aggregates are one of the major constituents of the pathological inclusions of frontotemporal dementia with motor BRAIN RESEARCH 1366 (2010) 1 – 8 ⁎ Corresponding author. Department of Surgery, Faculty of Medicine, University of British Columbia, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Fax: +1 604 322 0640. E-mail address: wjia@interchange.ubc.ca (W. Jia). 0006-8993/$ – see front matter © 2010 Published by Elsevier B.V. doi:10.1016/j.brainres.2010.09.099 available at www.sciencedirect.com www.elsevier.com/locate/brainres